The present invention relates generally to singulated die transport devices, and more particularly concerns die transport devices employing condition sensitive adhesive tape to receive, retain, and release the components in automated assembly processing.
Die transport devices are presently a staple item in today""s industry for manufacturing electrical devices. These transport devices are used to receive, retain and release small electrical components, also known as xe2x80x9cdie devices.xe2x80x9d These include, for example, single integrated circuits, chip transistors, chip capacitors, mechanical bonding pads, and outline transistors. Die devices typically are square or rectangular and about 0.024 inches in height or thickness. Pressure sensitive adhesive (PSA) tape is currently employed to secure the die devices to the carrier devices during transportation until installation of the components. Removal of a die device from a typical transport device using PSA tape requires a needle or some other device to pierce the tape affixed to the die device and displace the die device away from the tape. This removal process makes small integrated circuits susceptible to mechanical and electrical damage. At the minimum, a small divot is formed no matter how light the contact is between the needle and the die device. Further, the components are not consistently removed from the transport device depending on the size of the die device and the adhesive levels of the PSA tape. Since die devices are fragile and proper installation of these components is crucial, enhancing the handling of die devices associated with the transport device is extremely important.
There are many proposed solutions for improving the handling of die devices associated with a transport device. Three proposed solutions seek to eliminate improper retrieval of the die devices. One solution involves a system requiring the use of a tape known as xe2x80x9cembossed with coverxe2x80x9d tape. This system includes a carrier having a pocket formed therein for receiving the die device. Cover tape is affixed to the top surface of the carrier so as to secure the die device in place. A hole is formed in the bottom of the pocket to permit a needle or some other device to enter and displace the die device out of the pocket after the cover tape has been removed. Unfortunately, this technique does not eliminate the risk of mechanical and electrical damage associated with contact between the needle and the die device. Further, other problems arise in substituting cover tape for PSA tape. First, vibration forces resulting from the removal of the cover tape can cause the die device to come out of the pocket before being extracted from the pocket. Second, the cover tape, although transparent, prevents inspection of the die device at high magnification. Third, the cover tape must be sized according to the dimensions of the pocket proportioned for its respective die device. Finally, it is difficult to uniformly seal cover tape to the carrier.
Another solution involves a system that utilizes a tape known as xe2x80x9cpunched with coverxe2x80x9d tape. This system requires a carrier with a plurality of holes formed therein. Cover tape is placed on the bottom side of the carrier so as to completely cover the holes and provide a support for receiving the die device. Cover tape is also placed on the top of the carrier to secure the die device in position. To remove the die device, the cover tape on the top side of the carrier is removed and subsequently a needle pierces the bottom cover tape to displace the die device out of the pocket. This system also fails to resolve the risk of mechanical and electrical damage resulting from the contact between the needle and the die device. Further, the use of cover tape results in the same adverse effects experienced in using the first solution.
A third solution requires a system to employ strips of PSA tape. This system involves a carrier with a plurality of holes or openings. Strips of PSA tape are affixed to the bottom surface of the carrier so as to partially cover each hole and provide a support for receiving the die device. To remove the die device a needle passes through the gap between the strips of PSA tape, contacts the die device, and displaces it away from the tape and out of the carrier. Unfortunately, this system also fails to eliminate the risk of mechanical and electrical damage associated with the contact between the needle and the die device. Further, small pieces of adhesive material can remain on the bottom surface of the die device after removal and cause problems when the die device are soldered in the component placement process.
Therefore, a need exists for a singulated die transport with enhanced die device release to allow for proper inspection and extraction without undue risk of damage to the die device.
In accordance with the present invention, a die transport device includes condition sensitive adhesive tape. The condition sensitive adhesive tape is adhered to a bottom surface of a carrier plate within the transport device so as to cover a series of holes or openings formed in the carrier plate. The holes are subject to receive small electrical components, known as xe2x80x9cdie devices,xe2x80x9d such as single integrated circuits, wherein the bottom surfaces of the die devices adhere to the condition sensitive adhesive tape. In this regard, the carrier plate can have one or more holes or openings, depending on the size of the die device and/or the number of die devices needed. The size of the holes varies depending on factors such as the size of the die devices and width of the tape. A typical diameter of the hole is 1.5 mm.
In a preferred arrangement, heat sensitive adhesive tape is adhered to the bottom surface of the carrier plate within the transport device so as to cover the holes formed in the carrier plate. To secure the die devices in the transport device, the heat sensitive adhesive tape adheres to the bottom surfaces of the die devices contained within the holes. To release the die device from the transport device, the heat sensitive adhesive tape is heated to a point where the adhesive capacity of the tape has diminished. A suction force is then applied to remove the die devices from the transport device. The die devices can be deposited on a work surface, placed directly onto a circuit board, or the like, depending on the user""s needs.
In an alternate arrangement, ultraviolet light sensitive adhesive tape is adhered to the bottom surface of the carrier plate within the transport device so as to cover the holes or openings formed in the carrier plate. Using the ultraviolet light sensitive adhesive tape, the die devices are secured in the transport device on the tape in the same manner as described above. One side of the tape is adhesive and securely holds and retains the die devices in position in the carrier during transport. In order to remove the dies from the transport device, the tape is exposed to ultraviolet light so as to release the adhesive.